1. Field of the Invention
The present invention relates to an improved assembly for controlling the ground speed of an off-road vehicle and, more specifically, relates to an improved transmission linkage which allows simple interchangeability between foot and hand controls for controlling the ground speed of lawn tractors, lawn and garden tractors and front-mount mowers having variable speed transmissions, such as hydrostatic or continuously variable transmissions.
2 . Description of Related Art
It is well known to provide off-road vehicles, specifically lawn tractors, lawn and garden tractors, and front-mount mowers with systems for controlling their ground speed. Typically, variable speed transmissions such as hydrostatic transmissions or continuously variable transmissions utilized in off-road vehicles such as those listed above have used separate combinations of hand and foot controls to select the direction of travel and to control the vehicle speed.
One conventional system utilized to control the ground speed of the types of off-road vehicles mentioned above, includes a treadle pedal which is essentially a heel and toe forward and reverse control mechanism. With the treadle pedal control system, an operator normally places his foot on the pedal in such a way that the toe of the operator's foot would contact one portion of the treadle pedal and the heel would contact another portion. To drive the vehicle in the forward direction, the operator presses his toe forward thereby raising his heel off of the vehicle footrest. To change the direction of movement to reverse or to slow it down, the operator would increase the pressure on his or her heel until the vehicle eventually came to the neutral position and to a complete stop; and then continue pressing his heel down toward the foot rest in order to produce vehicle movement in the reverse direction.
The conventional treadle pedal system has proved to have three significant problems. The first relates to operator discomfort which results from the fore-and-aft movement of the foot. The second, somewhat related to the first, relates to the difficulty in modulating the vehicle's speed in either the forward or reverse direction because the conventional treadle pedal design requires that the operator keep his foot on both the forward control and reverse control portions of the pedal simultaneously. Third, because the operator's leg is suspended above the foot rest, and his foot is located on a movable pedal, the foot cannot maintain contact with the foot rest that could provide foot stability. Accordingly, vehicle speed control over rough terrain is sometimes difficult to regulate.
Another ground speed control system developed for off-road vehicles is the dual pedal side-by-side system. The details of this system are disclosed in U.S. Pat. No. 4,759,417 dated Jul. 26, 1988 issued to Wanie et al. and commonly assigned to the assignee of the present application, the disclosure of which is hereby incorporated by reference. Both pedals occasionally require that the right foot and leg be lifted and the foot placed on the correct pedal in order to move the vehicle in the desired direction.
A variation of a two pedal system wherein the forward pedal is closer to the front of the vehicle than the reverse pedal is disclosed in U.S. Pat. No. 5,048,638 dated Sep. 17, 1991 issued to Duncan et al. and commonly assigned to the assignee of the present application, the disclosure of which is hereby incorporated by reference.
These pedal systems are often coupled with a hand-operated "cruise control" lever which is generally used to maintain a specified forward speed, eliminating the need for constant application of foot pressure to keep the vehicle moving forward at a desired rate of speed.
Conventional hand controls for off-road vehicles require that the operator remove at least one hand from a steering wheel to reach a control lever and to move it to the appropriate location. During the movement of the operator's hand from the steering wheel to the control lever, the operator risks interrupting his or her his concentration from the task being performed with the vehicle in order to concentrate on moving his hand control to the proper position, thereby reducing productivity and operating comfort. Thus, there is presently a tendency toward providing such vehicles with foot controls for general use.
Therefore, many manufacturers of off-road vehicles supply base models of such vehicles with foot controls (and often the aforementioned "cruise control" lever). While there is a general trend toward the use of pedal systems, however, certain operators maintain a preference for hand controls. In addition, persons with certain physical characteristics or disabilities are unable to use a pedal system. Therefore, sporadic conversions are made from foot control systems to hand control systems. However, exchanging control linkages and components is often cumbersome, as drilling, welding, and/or custom fabrication may be required.
Accordingly, there is a need for an improved assembly for controlling the ground speed and direction of travel of maneuverable off-road vehicles having variable speed transmissions such as variable speed hydrostatic transmissions; which allows for quick, easy and inexpensive conversion between pedal and hand controls.